import { PUBLIC_COOKIES_SECURE, PUBLIC_DOMAIN } from '$env/static/public';
import { parseBool } from '$lib/env';
import type { Cookies } from '@sveltejs/kit';

interface CookieInfo {
	name: string;
	value: string;
	options: {
		SameSite?: 'Strict' | 'Lax' | 'None';
		Secure: boolean;
		Partitioned: boolean;
		HttpOnly: boolean;
		Expires?: Date;
		'Max-Age'?: number;
		Path?: string;
		Domain?: string;
	};
}

function parseCookieHeader(headerValue: string): CookieInfo {
	const [nv, ...options] = headerValue.split(';');
	const [name, value] = nv.split('=').map((v) => v.trim());
	const cookie: CookieInfo = {
		name,
		value,
		options: {
			Secure: false,
			Partitioned: false,
			HttpOnly: false
		}
	};

	options.forEach((option) => {
		const [key, value] = option.split('=').map((v) => v.trim());
		switch (key) {
			case 'Secure':
				cookie.options.Secure = true;
				break;
			case 'SameSite':
				cookie.options.SameSite = value as 'Strict' | 'Lax' | 'None';
				break;
			case 'Partitioned':
				cookie.options.Partitioned = true;
				break;
			case 'HttpOnly':
				cookie.options.HttpOnly = true;
				break;
			case 'Expires':
				cookie.options.Expires = new Date(value);
				break;
			case 'Max-Age':
				cookie.options['Max-Age'] = parseInt(value, 10);
				break;
			case 'Path':
				cookie.options.Path = value;
				break;
			case 'Domain':
				cookie.options.Domain = value;
				break;
		}
	});

	return cookie;
}

export function passthroughSession(response: Response, cookies: Cookies) {
	if (response.ok) {
		const cookieHeader = response.headers.get('Set-Cookie');
		if (!cookieHeader) {
			return;
		}
		const info = parseCookieHeader(cookieHeader);
		cookies.set(info.name, info.value, {
			httpOnly: info.options.HttpOnly,
			secure: parseBool(PUBLIC_COOKIES_SECURE),
			sameSite: 'strict',
			domain: PUBLIC_DOMAIN,
			expires: info.options.Expires,
			maxAge: info.options['Max-Age'],
			path: info.options.Path ?? '/'
		});
	}
}